# Thread: Trouble plotting a particular equation

1. ## Trouble plotting a particular equation

I'm trying to plot the following equation : y = random( floor(uv.x) ):

figure 1

I've tried other equations and they work just fine:

The problem starts when I try equations with steep angles like y = random(floor(uv.x)), they get their horizontal lines cut off

The color gets cut off at a certain angle.

I'm not sure what I'm doing wrong, but this is what I've tried so far:

Code :
```out vec4 color;

float Random(in float x) {
return fract(sin(x) * 1e4);
}

void main () {

vec2 uv     = gl_FragCoord.xy/ screen.xy;
vec2 ndc    = vec2(uv.x * 2.0 - 1.0, uv.y * 2.0 - 1.0);
uv.x        *= screen.x / screen.y;

uv -= 0.5;  // -0.5 <-> 0.5
uv *= 5.0;  // Zoom Out, if not we don't see much

vec4 final = vec4(0.0);
final.a = 1.0;

float i = floor(uv.x); // Integer Coords
float f = fract(uv.x); // Fractional Coords

// Calculate Graph

// This Works
// float u = f * f * (3.0 - 2.0 * f );
// float x = mix(Random(i), Random(i + 1.0), u);

float x = Random(i); // No horizontal Lines :(
float y = uv.y;

// Plot
float blur = 0.01;
final.r = smoothstep(x - blur, x, y); // bottom
final.r -= smoothstep(x - blur, x, y - blur);

color = final;

}```

I'm clearly not understanding something :/ I re-edited the entire question with new and shorter code. As always, thanks!

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